The present inventions relate to winding applications, one example of which is a continuous coil winding machine employing a flyer arm wire feed and a coil form with a plurality of stepped turn positions of progressively increasing size. More specifically it relates to apparatus for stabilizing the wire fed to a coil form for providing improved control of the position of wire strands or segments wrapped across the form in general, and in particular to the position of "crossover" that links adjacent coils of different sizes. In one particular aspect, the invention relates to a novel tension approach useful in stabilizing the wire fed to the coil form during the coil windings process; in another aspect, it relates to improving the "lay" of wire as it is wrapped about the form; in yet another, it relates to means for accommodating excess lengths of wire that intermittently briefly occur between the wire supply and coil form; and in still another form to methods and apparatus that reduce the stress on the insulation coating on wire being handled.
Automatic coil winding machines used, for example, to wind stator core windings of dynamoelectric machines are well known. In one known form of such machines, wire is wrapped around a coil form in a high speed manner by a flyer arm wire feed mechanism which is mounted for rotation about the coil form. Typically the coil form generally comprises a plurality of turn forming sections about which differently sized turns may be produced. Such forms also are adjustable so as to permit a given coil form to be used for winding coil groups for cores of different stack heights. For convenience in the following disclosure, it will be assumed that motor coils are being wound, although it will be appreciated that my invention itself may be used for other applications.
For a given motor design, it is usually desired to wind in a continuous manner a complete coil structure having a number of turn groups of progressively increasing size, i.e. with increasing sizes of mean turn length or turn circumference (circumference is used herein to denote turn perimeters that are rectilinear in shape, elipsoid, or oblong, as well as circular). This is accomplished by providing a coil form of stepped configuration with winding commencing on the smallest circumference form portion. When a sufficient number of turns have been wound, the relative position of the wire feeder (or flyer) and coil form is changed, usually by axial movement of the coil form, so as to cause the wire to jump to the next larger stage or portion of the coil form. This process is repeated with subsequent portions or stages of the form until a desired group of differently sized coils is completely wound.
In the course of the winding process, each group of turns (or coil) formed about a given stage of the coil form is caused to be placed in a predetermined position in a coil magazine or coil injection apparatus such that the relative position of the turns are maintained until the turns are injected in well-known manner into appropriate slots, for example, of a motor stator core. In order to assure that the wire is not stretched or broken during this injection process, proper crossover control during the winding process is important. That is to say it is well known that the transition or "jump" of the wire from one turn form position to the next in the winding process must occur at a predetermined angular position of the flyer arm relative to the coil form. Specifically, the transition must occur such that the jump wire leads from the smaller turn group at the end which is inserted into the magazine or coil injection apparatus ("tooling") to the larger turn at the trailing end, i.e. the end of the coil remote from the tooling. This is to assure that the circumferential length of the transition or jump wire is long enough to accommodate the injection process without being pulled up against the rear or bottom side of the stator core which, if allowed to occur, could cause the wire to be unduly stretched and possibly broken. Similarly, it is necessary to assure that crossover or jump does not occur until the required number of turns have been wound in the turn group in order to avoid the formation of stray turns of odd size. These various criteria have now been long known in the art and are discussed at length in Arnold et al U.S. Pat. Nos. 3,973,601 of Aug. 10, 1976; Arnold 3,967,658 of July 6, 1976; and Lauer U.S. Pat. No. 3,765,080 of Oct. 16, 1973. These three patents are assigned to the same assignee as the present application, and the entire disclosures of all three of these patents are incorporated herein by reference.
Wire jump that undesirably occurs in the middle of a turn group or that occurs on the wrong side of the coil form when transitioning between coil groups is known to be caused in some instances by unstabilized wire feed from the flyer arm to the coil form during the extremely high speed winding process. Wire stability is adversely affected by the sudden and drastic changes in wire feed rates caused by the circular rotation of the flyer arm about a coil form that is normally non-circular in configuration. The inertia of the wire causes the wire to whip or flop up and down outside its normal feed plane as it reaches the coil form. If the whip is sufficient in magnitude, the wire can land on the next higher (larger) turn form position resulting in an incorrect jump despite the fact that the form and flyer have not been changed in their relative positions.
Prior attempts to avoid this problem have taken the form of, for example, "halo" rings surrounding the coil form in the plane of the feed wire in an attempt to stabilize the wire against the occurrence of whip as it approaches the form. A similar attempted solution is the use of masking plates lying very close to the plane of the feed wire, the plate having an aperture aligned with the coil form and having sufficient through clearance to allow the coil turns to move into the receiving magazine or coil injection apparatus. Although such attempted solutions have been shown to provide some advantage in improving wire stability, they have not been entirely successful. In addition, they have the disadvantage of adding interfering structure in the vicinity of the coil form and flyer arm that make it difficult to perform machine set up and adjustment procedures.
Problems have also been encountered with some winding equipment in the nature of damaging the enamel or insulation on wire. Thus, in some applications, enamel is abraded from the wire by the flyer mechanism.
It is therefore an object of the present invention to provide an improved apparatus and methods that obviate the problems and disadvantages discussed hereinabove.
It is another object of the present invention to provide apparatus that improves crossover control in a coil winding machine of the type employing a high speed flyer arm rotating about a stepped configuration coil form.
It is a further object of the invention to provide improved apparatus and methods that substantially eliminate the adverse effects of wire inertia as it relates to unwanted jump of the feed wire to the next larger turn form position of the coil form.
It is a still further object of the invention to provide apparatus and methods that improve feed wire stability in a winding machine environment without the inconvenience of added structure around or near the coil form.
It is yet a further object of the invention to provide apparatus for a coil winding machine that is mounted for rotation with a flyer arm to stabilize the feed wire without unduly interfering with set up and machine adjustment procedures between winding operations.
It is yet another object of the invention to provide apparatus for the described coil winding machine that enables convenient adjustment for optimum wire stabilization with differing winding conditions and wire size and strength and the like.
It is yet still another object of the invention to provide improved methods and apparatus whereby wire enamel damage is minimized, and particularly while accomplishing various ones of the objects pointed out hereinabove.